Esterification of thionobenzene-phosphonyldichloride in the presence of 2-methyl-5-ethylpyridine



United States Patent 3,327,026 ESTERIFICATION 0F THIDNOBENZENE-PHOS- PHONYLDICHLORIDE IN THE PRESENCE OF Z-METHYL-S-ETHYLPYRIDINE Noboru Shindo, Tokyo, and Shinichi Wad'a, Kiyoshi ()ta, Fumio Suzuki, and Yoichi Ohata, all of Onoda-shi, Yamaguchi-ken, Japan, assignors to Nissan Kagaku Kogyo Co., Ltd., Tokyo, Japan, a corporation of Japan No Drawing. Filed July 23, 1963, Ser. No. 296,901 1 Claim. (Cl. 260-973) This invention relates to a process of producing o-ethylparanitro-phenylthionobenzenephosphonate, a known insecticide, in high yield. In the synthesis of o-ethylparanitro-phenylthionobenzenephosphonate from thionobenzenephosphonyldichloride, the latter is reacted with ethyl alcohol C H OH in a first stage reaction, thereby to obtain o-ethylthionobenzenephosphonylchloride S O C2115 and thereby reacting the resultant product with sodium paranitro-phenolate as the second stage reaction, o-ethylparanitrophenylthionobenzenephosphonate is obtained. Said first stage reaction is an esterification reaction, so that beside the resultant o-ethylthionobenzenephosphonyl chloride there remains unreacted thionobenzenephosphonyldichloride and with further undesired eserification, a small part of the product becomes o,o-diethylthionobenzenephosphonate S OCzHs O C 2H Thus, the reaction product contains in addition to oethylthionobenzenephosphonyl chloride, thionobenzenephosphonyl dichloride and 0,0-diethylthionobenzenephosphonate. These last two substances generate impurities when the first stage reaction product is condensed with sodium paranitrophenolate in the second stage reaction, or remain and are thus the greatest cause of lowering the purity of the final product.

This esterification reaction is a reaction of removing hydrochloric acid, and therefore a catalyst for removing hydrochloric acid is added. The catalyst to be employed affects the quality of o-ethylparanitrophenylthio-nobenzenephosphonate. Accordingly, it is very important to find an excellent novel catalyst. The process of the present invention employs 2-rnethy'1-5-ethyl pyridine as a catalyst for removing hydrochloric acid, which is superior to pyridine or other organic bases conventionally used, and better from the economical point of view in case of industrialization.

The synthesis of o-ethylparanitrophenylthionobenzenephosphonate is shown by the following Equations (1) and (II), with (I) and (II') representing undesired side reactions.

3,327,026 Patented June 20, 1967 OC2H5 S [I Cataiyst B li C1 NaO N02 C1 0,0-diparanitrophen0l thionobenzenephosphonate Other than the above-shown reactions various complex side-reactions are derived, but there is no serious error in considering only the principal reactions.

If the reaction velocity in the reaction (I) is represented by K and that in the reaction (I) 'by K the greater the value of K /K of the catalyst, the higher the OCzHz The reaction conditions of these comparative tests are shown in the following table.

Catalyst 2-methyl-5ethyl- Dimethyl aniline Pyridine pyridine i Esterification Reaction (the -PCii 63.3 g. (0.30 mol) 63.3 g. (0.30 moi) 63.3 g. (0.30 moi).

first stage reaction).

Condensation Reaction (the second stage reaction).

Reaction Product E hanoi (98.2%).

t Solvent- Reaction temperature p-Nitrophenoiate Impurities Total of the lay-product.

15.5 g. (0.3 mol x 1.10)- Toluene, 150 cc 16.9 g. (0.3 moi x 1.20) Toluene, 150 cc 15.5 g. (0.3 mol x 1.10). Toluene, 150 cc.

As described above, it is clear that Z-methyl-S-ethylpyridine stands out from others. Further, yields of other catalysts are shown in the following table.

Reaction Product 1 Yield purity OQNO:

CATALYST Tn'ethyiamine, percent 83. 75 1. 46 76. 4 a-Picoline, percent 82. 53 1.19 70. 2 fl-Picoline, percent. 86. 51 2.33 69.0 2,6-iutidine, percent 85. 63 3. 75 78. 1 Coiiidine Quinoline, percent.-. 82. 56 9. 46 73. 7 Tributylarnine, percent 58.83 13. 88 59. 5

1 Many side reactions.

The reaction conditions of these comparative tests were as follows: (a) Materials fed:

thionobenzenephosphonyldichloride, (0.30

The predominant advantages where industrialization is carried out by use of the catalyst of the present invention are indicated in the following:

(1) The catalyst of the present invention is the prodnet of a synthesis. The catalyst of the present invention can be easily synthesized from acetylene and ainrnonia, compared with coal system organo'basic materials. Furthermore, it is an intermediate product of vinylpyridine having use in the fiber field. It is economical and easily obtained.

(2) The catalyst employed in the present invention can be easily recovered.

2-methyl-5-ethylpyridine hydrochloride formed by the reaction is neutralized With sodium hydroxide, and thereafter extracted with benzene or toluene. Almost all of the resulting Z-methyl-S-ethylpyridine is transferred into the organic solvent layer. By distilling the layer, more than 90% of purified 2-rnethyl-5-ethylpyridine can be obtained.

As mentioned above, according to the process of the present invention, cost is lowered by using Z-methyl-S- ethylpyridine, compared with employing other catalysts.

The present invention is explained in detail by the following example.

6 EXAMPLE Materials fed:

T hionobenzenephosphonyldichloride (0.3 mol) g 63.3 Alcohol (98.2%), (0.3 mol X 1.10) g 15.5 Toluene (reaction solvent) cc 2-methyl-5-ethyl pyridine g 43.6

Reaction conditions:

Period for dropping of ethanol hrs 2 Reaction time hrs 5 Reaction temperature C '10 Treatment:

After removing HCl, washing is carried out With water and stirring is effected for 10 minutes. Toluene is distilled off leaving a reaction product which is relatively pure o-ethylthionobenzenephosphonyl chloride. Then, the reaction product is condensed with sodium paranitrophenolate to yield 0 ethylpar-anitrophenylthionobenzenephosphonate.

The product g 87.9 Purity percent 92.48 Yield do 83.7

References Cited UNITED STATES PATENTS 3/1959 Peterson et al 260-973 X 8/1962 Chupp 260-973 X CHARLES B. PARKER, Primary Examiner.

JOSEPH P. BRUST, Examiner.

BERNARD BIL-LIAN, FRANK M. SI'KORA,

Assistant Examiners.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,327,026 June 20, 1967 Noboru Shindo et al.

It is hereby certified that error appears in the above numbered p requiring correction and that the said Letters Patent should read as ent corrected below.

Column 1, line 54, for "thionobenzenephosphonate" read H thionobenzenephosphonate column 2, lines 50 to 55, for that portion of the formula reading Z Z read Z S stage line 33, after column 6, line 30, for "state" read "reaction" insert product Signed and sealed this 20th day of August 1968.

(SEAL) Attest:

Edward M. Fletcher, Jr. EDWARD J. BRENNER Commissioner of Patents Attesting Officer 

